1. Field of the Invention
Embodiments of the disclosure are directed to monitoring dormant or out-of-service fiber optics for layer 0 restoration.
2. Description of the Related Art
Turning up wavelengths in an optical link, especially in a DWDM (dense wavelength division multiplexing) system, is becoming time critical in terms of layer 0 restoration schemes. Any potential link failures can delay the wavelength turn up and therefore delay or fail the overall layer 0 restoration with respect to time. Such optical link failures include, but are not limited to, optical line fails, line fiber cut, extended span loss reach in any span that can drive the next amplifier block, or EDFA (erbium doped fiber amplifier) to shutoff or in input loss of signal (LOS) state. It is possible to have high back reflection present on the line fiber that could severely impact the performance of the optical channels. It can also drive down the amplifier output power to a lower value by triggering, for example, the amplifier safety mechanisms (e.g., automatic power reduction mechanism or APR). Any of the line amplifiers, for example, can be manually set to out-of-service that can shutdown the amp causing severe service interruption on that link.
If these traffic interrupting link disturbances can be detected ahead of time for any optical link, that link can be avoided during the phase of layer 0 restoration. Traffic impacting link disturbances can be detected when links are already carrying some level of traffic channels.
If the link remains dark either in day 1 installation when the link is not carrying any traffic or after fixing link down related conditions (e.g. fiber cut) where all services were earlier moved due to link failures, traffic may be reverted back on the home path after fixing the fault points. If the link is not verified ahead of time, any restoration or reversion action triggered over the dark link may fail due to the above mentioned link imperfections.